Electromagnetic relay



Dec. 5, 1939. w. R. ROSE ELECTROMAGNETIC RELAY Filed Jan. 2, 1957Patented Dec. 5, 1939 UNITED STATES PATENT OFFiCE ELECTROMAGNETIC RELAYWilliam Robert Rose, Coventry, England, assignor to The General ElectricCompany Limited,

London, England 7 Claims.

The present invention relates to electromagnetic relays, and has for itsobject the provision of a two-position relay having improved operatingcharacteristics, whilst at the same time emplglying as many standard orknown parts as pos- In telephone systems it is known to employ a relayhaving an L-shaped yoke, and an armature pivoting on a knife edge on thesaid yoke and acted upon by an operating coil carried by the yoke, thearmature being adapted to move contact springs arranged in piles whichare mounted on the same yoke. This type of relay is arranged to remainnormally in an unoperated position, the armature and contact springsmoving to an operated position and remaining so, only so long as currentis applied to the operating coil.

It is also known to construct a relay which remains in either of twopositions after a momentary energisation of an operating coil, having anarmature pivoted about an axis passing between the ends of the operatingcoils of the relay, the said armature being locked in either of itsextreme positions by means of a spring. This type of relay, however,suffers from the disadvantages that a number of special parts arerequired, and that a portion of the magnetic circuit is common to bothoperating coils, this tending to produce incorrect operation undercertain extreme conditions.

According, therefore, to the invention, a relay of the two-position typecomprises two entirely separate magnetic circuits, each one composed ofan operating coil and core, a yoke and an armature, the said magneticsystems being disposed side by side, the two armatures being sointerlinked by a rocking member that operation of one by a currentthrough its associated coil causes positive release of the other, theinterlinking mechanism being such that the armature last operatedremains in this position until the other armature is operated in turn.

In a preferred form of the invention two relay assemblies of the typeused in telephone systems are mounted side by side on a common plate.Their armatures are interlinked by a rocking member extending from oneto the other and pivoted about an axis passing at right angles through aline drawn parallel to, and midway between the axes of the operatingcoils of the relays. This said member carries an arm extending into thespace between the two relays, its end co-operating with a flat springbowed and supported between a V notch at one end and a further fiatspring at the other.

This latter spring is tensioned so as to efiect the curvature of theformer spring, the said tension being of suflicient strength toensurethat after the operation of one armature and consequent release of theother, the moving parts are maintained in this position until theenergisation of the operating coil of the released armature.

Either one or both armatures may operate one or more sets of contactsprings, and adjustments are provided whereby the retaining action ofthe bowed spring is compensated for varying contact spring loads.Further adjustments may be provided to compensate for the effects ofmanufacturing tolerances on the core lengths, and also to correct anypossible eccentricity of the pivot on which the member co-operating withthe two armatures is mounted.

Reference should now be made to the accompanying drawing, Figure 1 ofwhich shows a partly dismantled relay, Figure 2 a view of the relay seenfrom the armature end, and Figure 3 a part sectional view taken alongline A-A of Figure 2.

Referring to Figure 1, this shows one of the magnetic circuits employedand the device for holding the armatures of the relay in either one oftwo positions without energisation of either of the operating coils. Themagnetic circuit shown comprises a coil I, wound on a core 3, the latteracting upon an armature l pivoted about a knife edge 2. This knife edgeis part of a yoke 5 which is L-shaped, and to which is clamped theoperating coil and core. The armature, yoke and core of the operatingcoil form a magnetic circuit, and the whole is mounted on a base plate Iby means of screws.

In known types of relays having a yoke similar to that described, thearmature is normally held away from the core 3 by the tension of flatcontact-making springs mounted in insulating supports on the yoke. Asthe relay according to the invention has to hold one of the armaturesoperated without energisation of either of the operating coils, a centrepiece 6 fixed to the base plate I is provided, this centre piececarrying a rocker 9 pivoted about an axis N]. This rocker is providedwith a transverse portion one end of which co-operates with one armaturewhile the remaining end engages with another armature forming part ofthe second coil assembly (not shown), which is exactly similar to thatdisclosed in the drawing, this second assembly being fixed to the baseplate by screws passing through the holes 52. As best seen in Figs. 2and 3, each end of the rocker 9 carries a bead 32 which bears upon oneof the armatures and is locked thereto by means of a Z-shaped bracket llscrewed to the armature. These couplings permit the free rotation of therocker and both armatures about their respective axes.

The rocker also carries an arm M which extends into the space betweenthe two magnetic circuits. The end of this arm is forked and engageswith the middle of a bowed spring 13 which at one end engages with a Vgroove in the centre member 6 and at the other end with a slot in a pinl! which slides freely in a hole in the centre member 5. Pressure isapplied to the pin I1 and hence to the spring 13 by means of a furtherspring 2!! this latter spring being fixed firmly to the centre member 6by screws 2|. The tension on this spring 20 is such as to maintain thespring 83 in a bowed state, the arrangements being such that when eitherarmature is attracted sufiiciently strongly by its operating coil tomove the spring ii! from one extreme position to the other, the armaturerocking member and contact springs are retained in this latter position,even though the energisation of the operating coil is removed.Subsequent energisation of the operating coil moves the assembly back toits previous position.

Relays of the type described may be required to carry either few or manycontact making springs. As shown, each armature acts upon two sets ofchangeover contact springs, but many more than these can be carried byeach yoke. This means that the tension acting on each armature varybetween wide limits so that in order to maintain the armatures androckers in either of twopositions independently of the spring load, awidely varying force must be applied to the lower end of the spring l3.An adjustment for this force is provided by applying pressure to thespring 20 by means of a screw 22 having a frustro-conical head, thescrew being mounted in and engaging with a thread on the centre piece 6.The slot in the screw head is accessible from the front of the relayeven when the latter is mounted and in position on a rack. Rotation ofthe screw in a clockwise direction applies increased pressure to thespring 2!! and hence through the pin I1 to the spring l3. Rotation inthe opposite direction reduces the pressure applied to spring I3.

It will be seen from Fig. 2 that the two operating coils lie with theiraxes parallel, the armatures operating on knife edges 2 and being retained thereon by means of the screws and springloaded washers M as shownin Figs. 1 and 3. The contact springs are supported near their frontends by means of a stepped insulator 25 and are fixed at their rear endsbetween insulating members 26. The clip 21 mounted on the front of therocker has a bent over extension 28 which retains a pin in positionthrough the rocker, this pin acting as the axis Ill about which therocker rotates.

It will be noticed that since the two magnetic circuits of the relay arecomplete in themselves, the centre member 6 can be and is preferably ofa non-magnetic material. This assists inpreventing false operation ofthe relay caused by interaction of the flux produced by the two coils.some of which may traverse the centre member if it is of magneticmaterial.

Two further adjustments are provided to take care of inequalities likelyto arise during the manufacture of the relay. The first of these enablesthe axis on which the rocker pivots to be moved in a direction towardsor away from the fixing plate of the relay. This facility is afforded bymeans of the U-shaped member 30, which is fixed to the centre piece 6 bythe two screws 2|. This member has two slotted holes, one in each end,through which the screws pass. When the screws are loosened the membercan be moved in a direction parallel to the centre line of the centrepiece 6, carrying with it the pin on which the rocker rotates, and hencethe rocker. This enables compensation to be effected for varying corelengths and also for varying travels required on the armatures.

Another adjustment is provided in the fixing of the forked arm M to therocker. This arm is fixed by means of two screws 3!, both of thesescrews passing through holes which are extended slightly sideways. Whenthe arm is fixed centrally on the rocker, all adjustments are correctfor an equal number of spring sets, and an exactly equal length ofcores. Should one of the cores be slightly longer than the other themean position of the rocker is displaced slightly from a true positionat right angles to the plane of the centre piece, this displacing thearm [4 in the gap between the two magnetic assemblies. In order toreplace the arm on the exact centre line, the two screws are loosenedand the arm moved to one side or the other depending upon whichdirection the inaccuracy is to be corrected. Tight ening the two screwsnow enables the arm to function properly.

This adjustment also provides means for correcting the eccentricity ofthe pin in which. the rocker pivots. Correction is performed in a mannersimilar to that described for inequality of core length. In addition,this adjustment enables the tension provided on the arm by the bowedspring to be adjusted unevenly on each side, this providing correctionfor unequal numbers of contact springs operated by the two armatures.Thus if one armature carries one set of contact springs and the otherarmature two sets, the relay is first adjusted so that the rocker is atright angles to, and the arm on, the centre plane of the relay, then thearm is moved sideways by loosening the two screws 3! until the pressureof the bowed spring on the armature compensates for the unequal load. Bythis means it is possible for the same current applied to each operatingcoil in turn to move the relay from one side to the other, the bowedspring retaining the armature in either of its two extremes.independently of the unequal load.

I claim:

1. An interlinking device adapted for mounting on the common base midwaybetween two similar relays to maintain the armatures thereof in oppositepositions, said device comprising a center supporting structure, anintegral member associated with the armatures. of the relays andarranged to rock on an axis of the center structure midway between saidrelays, a pin, flat springs, and an arm with one end rigidly attached tosaid integral member and the other end terminating in a fork engagingthe middle of one of said springs supported in a bowed position betweena V notch in said center structure and a slotted end of said pin whichis free to move and extends through a hole in said structure, and saidpin conveying pressure of another flat spring to maintain the bow in thefirst named spring.

2. An electromagnetic structure comprising two similar relays mountedside by side, a common interlinking device mounted between them, saidinterlinking device comprising a rocking member pivotally associatedwith the armatures of said relays for holding the operated relay operated after said relay is deenergized and until the associated relay isenergized and preventing operation of the associated relay while theoperated relay is energized, an arm, as a unitary part of said rockingmember, extending into the space between the relays and terminating in aforked end, a flat spring in contact at its midpoint with the forked endof said arm, and variable means for causing said spring to bow to eitherside of its center line.

3. An electromagnetic structure comprising two similar relays mountedside by side on a common plate, an interlinking device with supportingstructure mounted between the relays on said plate, said devicecomprising an integral member interlinking the armatures and rocking onan axis passing midway between the armatures and parallel to saidmounting plate, an arm rigidly attached to said integral memberterminating in a forked end extending into the space between the relays,a flat spring supported in a bowed position and in association at itsmidpoint with the forked end of said arm, thus insuring one armatureremaining in an operated position and the other in a normal position,another flat spring bearing against said first spring to maintain saidbowed position, and means for varying the tension of the latter toeffect the tension of the first named spring.

4. In combination with two similar relays mounted side by side buthaving unequal spring loads an interlinking device supported between therelays insuring that either one remains operated while the other is atnormal, said interlinking device comprising a rocking member having arelative association with each armature and rocking on an axis midwaybetween the armatures and parallel to the mounting plate, an arm,adjustably attached to said rocking member, terminating in a forked endextending into the space between the relays, a flat spring supported ina bowed position and associated at its midpoint with the forked end ofsaid arm, means for varying the amount of bowing of said spring andmeans for varying the association of said arm with said rocking memberto compensate for differences in the armature spring loads.

5. An electromagnetic relay comprising two separate relays disposed sideby side each having an operating coil and a core, a yoke and anarmature, an interlinking mechanism for holding the armatures in eitherone of two positions without energization, an integral member thereinpivotally mounted on an axis perpendicular to a plane containing theaxis of the armature and passing midway between the armatures so thatoperation of one armature by a current through its operating coil causesthe positive release of the other armature, the interlinking mechanismbetween the two armatures being such that the armature last operatedremains in this position until the other armature is operated in turn.

6. A relay comprising two separate electromagnetic systems disposed sideby side each having an operating coil and a core, a yoke and anarmature, a device for holding said armatures in either one of twopositions without energization of their operating coils, an interlinkingrocker therein extending from one armature to the other armature andpivoted about an axis at right angles to a plane passing through theaxis of the armatures and midway between the axis of the operatingcoils, flat springs, one spring bowed between a V notch at one end andanother of said springs at the other end, an arm carried by said rockerextending between the relays and interacting with said one springtoretain said armature in the position to which they are last operated.

7. An electromagnetic arrangement, comprising two relays disposed sideby side each having an operating coil and core, a yoke and an armature,an interlinking member for holding the armatures of said relays ineither one of two alternate positions without energization, said memberextending from one armature to the other armature and pivoted about anaxis passing midway between the armatures at right angles to a planeincluding the axis of said armatures, fiat springs combined so that afirst spring rigidly fixed at one end may bear on a second spring sothat said second spring is maintained in a bowed position between saidrelays, and an arm extending from said member to the bowed portion ofsaid second spring for retaining said armatures in one of saidpositions.

WILLIAM ROBERT ROSE.

